000 AXNT20 KNHC 171751 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SUN OCT 17 2010 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N22W 7N29W 10N36W 7N45W 8N51W. A SURFACE TROUGH IS ANALYZED JUST OFFSHORE OF W AFRICA ALONG 17N19W TO 9N20W. AN ASCAT SCATTEROMETER PASS INDICATES SHARP LOW-LEVEL CYCLONIC FLOW ABOUT THE AXIS. NUMEROUS STRONG CONVECTION IS E OF THE AXIS FROM 13N-17N BETWEEN 14W-17W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-19N BETWEEN 14W-21W. A SECOND EMBEDDED SURFACE TROUGH IS FROM 10N27W TO 14N26W WITH SCATTERED MODERATE CONVECTION FROM 10N-14N BETWEEN 23W-28W. SIMILAR ACTIVITY IS ALSO FROM 3N-8N BETWEEN 23W-30W. A SURFACE TROUGH IS ALSO IN THE CENTRAL TROPICAL ATLC ALONG 16N35W TO 7N39W WITH A SURFACE LOW ALONG THE TROUGH NEAR 11N38W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 4N-10N BETWEEN 31W-42W. ALL THREE OF THESE SURFACE TROUGHS ARE EMBEDDED IN A LARGE SCALE CYCLONIC GYRE WHICH IS CONTRIBUTING TO THE SMALLER PERTURBATIONS OF EACH TROUGH. THE PRESENCE OF AN UPPER LEVEL TROUGH TO THE N IS ALSO CONTRIBUTING TO THE LARGE AREA OF CONVECTION. ...DISCUSSION... GULF OF MEXICO... A LARGE SCALE UPPER LEVEL RIDGE COVERS THE GULF OF MEXICO WITH AXIS FROM THE NW CARIBBEAN TO THE MIDDLE CENTRAL CONUS PROVIDING DRY SWLY FLOW ALOFT. THE RIDGE SUPPORTS SURFACE RIDGING ACROSS THE SE CONUS AND THE GULF ANCHORED BY A 1022 MB HIGH S OF LOUISIANA NEAR 29N91W. LIGHT ANTI-CYCLONIC SURFACE WINDS ARE AROUND THE RIDGE ALONG WITH MOSTLY CLEAR SKIES BESIDES A FEW PATCHY FAIR WEATHER CUMULUS CLOUDS. SOME OF THESE CLOUDS MAY BE PRODUCING ISOLATED SHOWERS N OF THE YUCATAN PENINSULA AND IN THE WRN BAY OF CAMPECHE. EXPECT FAIR CONDITIONS TO CONTINUE ACROSS THE BASIN AS HIGH PRESSURE LINGERS OVER THE AREA. CARIBBEAN SEA... SHOWERS/THUNDERSTORMS CONTINUE ACROSS THE SW CARIBBEAN POSING A THREAT FOR FLOODING ACROSS PORTIONS OF CENTRAL AMERICA. A SURFACE TROUGH IS ANALYZED FROM NEAR 17N76W TO A 1009 MB SURFACE LOW OFF THE COAST OF PANAMA NEAR 11N78W WITH THE TROUGH CONTINUING SSW ACROSS COSTA RICA TO NEAR 9N86W. THIS TROUGH IS EMBEDDED WITHIN A LARGE CYCLONIC GYRE THAT HAS BEEN SITUATED ACROSS THIS PORTION OF THE BASIN FOR SEVERAL DAYS. SURFACE CONVERGENCE ALONG WITH DIFFLUENCE ALOFT BETWEEN UPPER RIDGING COVERING THE WRN AND CENTRAL CARIBBEAN AND CYCLONIC FLOW ALOFT ACROSS THE ERN PACIFIC ARE PRODUCING SCATTERED SHOWERS/THUNDERSTORMS FROM N OF PANAMA TO 16N BETWEEN 74W-85W IMPACTING PORTIONS OF PANAMA...COSTA RICA...AND NICARAGUA. TOTAL PRECIPITABLE WATER IMAGERY INDICATES AN AREA OF HIGH MOISTURE LEVELS ACROSS THIS AREA. A FEW ISOLATED SHOWERS/THUNDERSTORMS EXTEND INTO THE NW CARIBBEAN FROM 16N-21N BETWEEN 80W-85W. THE REMAINDER OF THE ERN HALF OF THE BASIN IS EXPERIENCING MOSTLY FAIR WEATHER UNDER THE INFLUENCE OF DRY AIR ALOFT AROUND THE AFOREMENTIONED UPPER LEVEL RIDGE THAT IS ACROSS THE WRN AND CENTRAL CARIBBEAN. UPPER LEVEL CYCLONE IS SITTING OVER THE LESSER ANTILLES...BUT IS CAUSING NO SIGNIFICANT WEATHER. EXPECT CONTINUED SHOWER ACTIVITY ACROSS THE SW CARIBBEAN AS THE LOW PRESSURE SYSTEM MOVES NW INCREASING THE PROBABILITY FOR SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF NRN CENTRAL AMERICA. ATLANTIC OCEAN... AN UPPER LEVEL CYCLONE NEAR NOVA SCOTIA WITH TROUGH AXIS EXTENDING TO THE SW SUPPORTS A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N50W CONTINUING ALONG 26N58W 24N70W BECOMING STATIONARY TO NE CUBA NEAR 21N75W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 90 NM OF THE FRONT BETWEEN CUBA AND THE BAHAMAS...AND WITHIN 90 NM AHEAD OF THE FRONT BETWEEN 66W-73W. ISOLATED SHOWERS ARE WITHIN 90 NM AHEAD OF THE FRONT ELSEWHERE. A DRY STABLE AIR MASS IS LEFT IN THE WAKE OF THE FRONT PROVIDING FAIR CONDITIONS ACROSS THE SW N ATLC. AHEAD OF THE FRONT...A WEAK 1014 MB HIGH IS NEAR 26N48W SUPPORTED BY AN UPPER LEVEL RIDGE EXTENDING FROM AN ANTI-CYCLONIC CENTER NEAR 10N50W WITH AXIS TO NEAR 41N41W. FARTHER E...A SURFACE TROUGH EXTENDS ALONG 32N24W 27N28W 21N45W SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING FROM THE AZORES ISLANDS TO W OF THE CAPE VERDE ISLANDS. POSSIBLE ISOLATED SHOWERS ARE ALONG THE SURFACE TROUGH AXIS. THE UPPER TROUGH IS HELPING ENHANCE CONVECTION ALONG THE ITCZ. WEAK SURFACE RIDING IS ACROSS THE FAR E ATLC SUPPORTED BY A 1018 MB HIGH NEAR 31N19W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON